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Hexagonal ferrite magnetic particle and method of manufacturing the same, and magnetic recording medium

a magnetic particle and hexagonal ferrite technology, applied in the field of manufacturing a hexagonal ferrite magnetic particle, can solve the problems of particle forming an aggregate, and hard particles of hexagonal ferrite, and achieves the effects of reducing the abrasion of the dispersion medium, high coercive force, and high density recording

Active Publication Date: 2011-10-06
FUJIFILM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a hexagonal ferrite magnetic particle that can be used as a ferromagnetic material in magnetic recording media, particularly high-density recording media. The particle has a coercive force of 159 to 318 kA / m and a specific surface area ranging from 50 to 100 m2 / g. The particle is non-aggregated, meaning it has not formed aggregates during crystallization processing, which can cause issues in magnetic recording media. The particle has a high purity and is suitable for use in high-density recording media. The invention also provides a method for manufacturing the particle and a magnetic recording medium comprising the particle. The technical effects of the invention include reducing dispersion medium abrasion, inhibiting the generation of fatty acid metal salts, and improving the performance of magnetic recording media.

Problems solved by technology

However, repeated washing during the acid treatment may cause particles of hexagonal ferrite to form an aggregate.
Further, the particles themselves become hard due to the coating of Al or the like on the aggregate, which is presumed to cause abrasion of the dispersion medium during dispersion processing.

Method used

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  • Hexagonal ferrite magnetic particle and method of manufacturing the same, and magnetic recording medium
  • Hexagonal ferrite magnetic particle and method of manufacturing the same, and magnetic recording medium
  • Hexagonal ferrite magnetic particle and method of manufacturing the same, and magnetic recording medium

Examples

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Effect test

example 1

[0095]Prescribed quantities of H3BO3 for B2O3, Al(OH)3 for Al2O3, BaCO3 for BaO, and Fe2O3 were weighed out so as to yield, based on conversion to the oxide, 23.0 molar percent of B2O3, 8.7 molar percent of Al2O3, 37.0 molar percent of BaO, and 31.3 molar percent of Fe2O3, charged to a mixer, and mixed. The mixture was charged to a two-liter platinum crucible, melted, and cooled with water-cooling rolls, yielding an amorphous material. A 600 g quantity of the amorphous material obtained was charged to an electric furnace, heated by 4° C. / minute to 720° C., and maintained at that temperature for five hours to cause hexagonal ferrite to crystallize (precipitate). Next, 600 g of the heat treated product after the crystallization was coarsely pulverized in a mortar and charged to a three-liter pot mill. Pulverization was conducted for four hours in a ball mill with 5 kg of Zr balls 5 mm in diameter and 1.2 kg of pure water. Subsequently, the pulverized liquid was separated from the ball...

example 2

[0096]Prescribed quantities of H3BO3 for B2O3, Al(OH)3 for Al2O3, BaCO3 for BaO, and Fe2O3 were weighed out so as to yield, based on conversion to the oxide, 26.3 molar percent of B2O3, 5.4 molar percent of Al2O3, 37.0 molar percent of BaO, and 31.3 molar percent of Fe2O3, charged to a mixer, and mixed. (A portion of the Fe was replaced with Co=0.5 at %, Zn=1.5 at %, and Nb=1 at %). The mixture was charged to a two-liter platinum crucible, melted, and cooled with water-cooling rolls, yielding an amorphous material. A 600 g quantity of the amorphous material obtained was charged to an electric furnace, heated by 4° C. / minute to 700° C., and maintained at that temperature for five hours to cause hexagonal ferrite to crystallize (precipitate). Next, 600 g of the heat treated product after the crystallization was coarsely pulverized in a mortar and charged to a three-liter pot mill. Pulverization was conducted for four hours in a ball mill with 5 kg of Zr balls 5 mm in diameter and 1.2 ...

example 3

[0097]Prescribed quantities of H3BO3 for B2O3, Al(OH)3 for Al2O3, BaCO3 for BaO, and Fe2O3 were weighed out so as to yield, based on conversion to the oxide, 30.4 molar percent of B2O3, 1.3 molar percent of Al2O3, 37.0 molar percent of BaO, and 31.3 molar percent of Fe2O3, charged to a mixer, and mixed. (A portion of the Fe was replaced with Zn=1.5 at % and Nb=0.75 at %). The mixture was charged to a two-liter platinum crucible, melted, and cooled with water-cooling rolls, yielding an amorphous material. A 600 g quantity of the amorphous material obtained was charged to an electric furnace, heated by 4° C. / minute to 660° C., and maintained at that temperature for five hours to cause hexagonal ferrite to crystallize (precipitate). Next, 600 g of the heat treated product after the crystallization was coarsely pulverized in a mortar and charged to a three-liter pot mill. Pulverization was conducted for four hours in a ball mill with 5 kg of Zr balls 5 mm in diameter and 1.2 kg of pure ...

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Abstract

An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle comprising melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material; subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment; collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on Al2O3 conversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority under 35 USC 119 to Japanese Patent Application No 2010-083612 filed on Mar. 31, 2010, and Japanese Patent Application No. 2010-233775 filed on Oct. 18, 2010, which are expressly incorporated herein by reference in their entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle, and more particularly, to a method of manufacturing a hexagonal ferrite magnetic particle that is suitable for use in manufacturing a particulate magnetic recording medium by a glass crystallization method.[0004]The present invention further relates to a hexagonal ferrite magnetic particle obtained by the above method, and a particulate magnetic recording medium comprising the above hexagonal ferrite magnetic particle.[0005]2. Discussion of the Background[0006]Recently, ferromagnetic metal particles have co...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B5/706H01F1/04G11B5/714
CPCB82Y30/00Y10T428/2982C01G49/0036C01P2006/12C01P2006/42C04B35/2683C04B35/6262C04B35/62665C04B35/62813C04B2235/3215C04B2235/3218C04B2235/3251C04B2235/3274C04B2235/3275C04B2235/3284C04B2235/3409C04B2235/5409C04B2235/5454C04B2235/767G11B5/70678G11B5/714H01F1/11G11B5/712C01G49/0018H01F1/0315
Inventor SUZUKI, HIROYUKIYAMAZAKI, NOBUO
Owner FUJIFILM CORP
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